BUG: test were not added to GENERATED_TEST_SOURCE
BUG: test were not added to GENERATED_TEST_SOURCE

In order to trigger the generation of test files, every output filename
should be added to the variable GENERATED_TEST_SOURCE. Files listed in
this variable are dependencies for the test executable and therefore
their custom commands get lined up in the chain of execution at build time.

kaspermarstal/SimpleElastix,richardbeare/SimpleITK,hendradarwin/SimpleITK,hendradarwin/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,hendradarwin/SimpleITK,blowekamp/SimpleITK,blowekamp/SimpleITK,hendradarwin/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,SimpleITK/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,InsightSoftwareConsortium/SimpleITK,richardbeare/SimpleITK,kaspermarstal/SimpleElastix,hendradarwin/SimpleITK,InsightSoftwareConsortium/SimpleITK,blowekamp/SimpleITK,hendradarwin/SimpleITK,richardbeare/SimpleITK,InsightSoftwareConsortium/SimpleITK,hendradarwin/SimpleITK,hendradarwin/SimpleITK,richardbeare/SimpleITK,kaspermarstal/SimpleElastix,richardbeare/SimpleITK,kaspermarstal/SimpleElastix,SimpleITK/SimpleITK,SimpleITK/SimpleITK,blowekamp/SimpleITK,InsightSoftwareConsortium/SimpleITK,kaspermarstal/SimpleElastix,blowekamp/SimpleITK,blowekamp/SimpleITK,SimpleITK/SimpleITK,richardbeare/SimpleITK,kaspermarstal/SimpleElastix,SimpleITK/SimpleITK,InsightSoftwareConsortium/SimpleITK,kaspermarstal/SimpleElastix,blowekamp/SimpleITK,blowekamp/SimpleITK,SimpleITK/SimpleITK